MUSCLE PHYSIOLOGY

Question 1

what are the 3 energy systems

Answer 1

1. phosphagen system
2. glycolytic
3. oxidative

Question 2

which energy system is used when

Answer 2

the phosphagen system and glycolytic system are used in intermittent bouts of high intensity exercise where oxygen is not needed and the regeneration of ATP is required rapidly
eg: sprinting
-the oxidative system kicks in in endurance training of lower intensity

Question 3

in ascending order list the systems according to their rate of ATP production

Answer 3

1. oxidative
2. slow glycolytic
3. fast glycolytic
4. phosphagen

Question 4

what are the adaptions that occur to anaerobic training

Answer 4

1. neural
2. muscular
3. endocrine
4. cardiovascular

Question 5

what are the neural adaptations that occur

Answer 5

1. increased firing rate of neurons
2. synchronization of the neural discharge
3. increased agonist recruitment
4. decreased inhibitory mechanisms
   - the motor cortex activity increases and so there is increased recruitment of motor units

Question 6

when do the neural adaptations occur

Answer 6

6-10 weeks into the training programme; before any muscular adaptations can occur

Question 7

what is the size principle

Answer 7

principle by which motor units are recruited. done in an ascending fashion from low to high threshold motor units ie; according their the recruitment threshold and force production
- the low threshold motor units that recruit slow twitch type 1 muscle fibres are recruited first and then as the exercise load increases; the high threshold motor units containing fast twitch, type II muscle fibres are recruited

Question 8

how would an athlete gain maximal force production

Answer 8

by activating all motor units so as to recruit all available muscle fibres

Question 9

what is selective recruitment

Answer 9

this is when the size principle is overruled and the high threshold motor units are activated out of turn ie; before the low threshold motor units.
- this is neccesary in times where great force production is required rapidly ie; sprinting or weight lifting

Question 10

how is the neuromuscular junction adapted with training

Answer 10

1. increased CSA of the synapses
2. increased terminal branching and synapse dispersion
3. increased ach receptors in the motor end plate

Question 11

how are the muscular reflexes adapted with training

Answer 11

1. the stretch reflex and muscle spindle increase in force production with training and so they are able to generate more force in a contraction without any additional energy required to generate that force

Question 12

what is the main muscular adaptation that occurs with exercise

Answer 12

hypertrophy: enlargement in the CSA of muscle fibres

Question 13

what does hypertrophy involve

Answer 13

1. increase in actin and myosin production
2. increase in the number of myofibrils in the fibre

Question 14

how does training induced actin and myosin synthesis differ between trained and untrained individuals

Answer 14

the increase in synthesis of these 2 proteins post exercise remains elevated for longer in untrained individuals
-this is why untrained individuals experience more rapid exercise induced muscle hypertrophy

Question 15

how is the hypertrophy process regulated

Answer 15

by the lysosome

Question 16

explain the steps of hypertrophy

Answer 16

1. contraction in the muscle activates a mechanoreceptor
2. this activates enzymes producing PA so PA levels increase and can bind to mTOR.
3. this also activates the enzyme producing erk so that erk can inhibit the action of TSC-2 on rheb.
4. so rheb can also now bind to mTOR
5. active mTOR stimulates protein synthesis
6. which leads to hypertrophy

Question 17

what is the function of satellite cells

Answer 17

-they are undifferentiated cells that can be activated during resistance training to proliferate and differentiate into myocytes that will fuse to existing myofibres. this means they donate extra nuclei to the fibres which allows for increased protein synthesis and thus; additional fibrils to be made.
-they also function in muscle injury where they are activated by the damage and proliferate and migrate to the damage site. then they will differentiate into myoblasts that fuse to form myotubes that further fuse to form myofibrils =replace the damaged tissue

Question 18

what is hyperplasia

Answer 18

the increase in the number of fibres by longitudinal fibre splitting

Question 19

when is hyperplasia seen in humans

Answer 19

amongst steroid users. because they reach an upper limit in fibre size they then experience hyperplasia

Question 20

what is the difference in fibre size change between type 1 and 11 fibres

Answer 20

type 2 fibres have a greater capacity to increase in size than type 1 and so those born with more type 2 fibres are going to be able to increase their muscle mass by more

Question 21

fibre type transitions with exercise

Answer 21

see a transition from type 11x to 11a ie; to a more oxidative kind
-cannot change the amount of type 1 and 11 fibres you have

Question 22

what happens to the pennate angle with exercise

Answer 22

this is the angle that a muscle projects from its tendon at.
-this angle seen to increase with training
-this increase allows for greater force production and greater increase in CSA of the fibres